Patent GB-1106713-A (GB)
Title: Sharpeners for chain saws
IPC: B23D63/16
Filed: 1966-05-23
Abstract: 1,106,713. Sawing. OMARK INDUSTRIES, Inc. 23 May, 1966 [21 May, 1965], No. 22925/66. Heading B5L. [Also in Division B3] A sharpener for a chain saw having a saw chain 30 advanced along a predetermined path having an arcuate portion comprises an elongated sharpening member 50 having an arcuate sharpening, surface conforming generally to the path of the tips of the projecting elements of the saw chain as it is advanced along the arcuate portion of the path, and an actuator for moving the sharpening member from a position out of engagement with the tips into engagement therewith and also for moving the member back and forth across the saw chain between extreme positions in which sides of the sharpening surface are completely between the extreme lateral edges of the tips so that the sharpening surface is uniformly worn across the entire width thereof. The sharpening member is bonded to a holding shoe 72 releasably secured to an arm 78 formed with a bearing portion (98, Fig. 3) slidable and rotatable on a pin 90 mounted in a casing 38 which is securable to the main casting 24 of the chain saw by the nuts 36. A spring 102 acts between the casing 38 and bearing portions to urge the arm anti-clockwise, as viewed in Fig. 2, and the sharpening member 50 away from the saw chain when it runs over the driving sprocket 26. The spring also urges the arm along the pin 90 to a position in which it is out of the plane of the saw chain and driving sprocket (shown solid in Fig. 5). The upper end of the arm 78 is formed with an end portion 110 which extends through an L-shapbd slot (112, Fig. 4) in the upper flange (40) of the, casing 38. In the inoperative position of the arm, the end portion 110 engages a notch (141). When the saw chain is to be sharpened, the arm is moved against the force of the spring first to disengage the portion 110 from the notch and is then moved along the rod, the portion moving along the slot until, when the arm is again rotated, the portion moves towards a block 130 adjustable by a screw 138 to determine the amount of sharpening to be effected. During sharpening, the saw chain is driven by the motor of the chain saw and the arm is reciprocated along the pin 90 by an amount determined by the movement of the portion between faces (143 144) of the slot so that the abrasive surface 52 is uniformly worn across its width. The movement of the arm is effected by use of a handle (114, Fig. 3) having a hooked or grooved end portion 116 engaging a bore 118 in the arm adjacent the pin 90. In another embodiment, the abrasive member is bonded to a shoe releasably secured to an arm mounted on a sleeve slidable and rotatable in a bearing on the frame casting of the chain saw, a spring acting to urge the abrasive member away from, and out of the plane of, the saw chain (230). The upper end of the arm has an end portion for engagement with an adjustable block for determining the amount of sharpening. The sharpening member is designed to have a life slightly longer than that of the saw chain so that when the latter is replaced so is the sharpening member. The saw chain consists of slitters 54, 55, side rakers 56, 57 and centre rakers 58, the width of the slitters being higher than the rakers. Depth gauges 60, 61 may be provided.